1. Field of the Invention
The present invention relates to a rotary impacting apparatus capable of providing high-frequency impacting force.
2. Description of the Related Art
Generally, an impacting apparatus such as a concrete breaker utilizes expansive force of compressed air or a combination of a motor and a crank mechanism for reciprocating an impacting piston in the main body. When reciprocated, the impacting piston repetitively hits a reciprocating implement supported at an end portion of the main body in an axial direction.
In the impacting apparatus of the above type, the impacting piston is forcibly reciprocated, so that the main body of the impacting apparatus will unfavorably be vibrated due to reaction from the impacting piston in motion. In addition, it is difficult to increase the frequency of reciprocation of the impacting piston due to the inertial mass of the impacting piston.
In order to overcome the above problems, the applicant of the present application proposed a rotary impacting apparatus as disclosed in U.S. Pat. No. 5,488,997. This rotary impacting apparatus includes a rotor which is rotatably supported by a housing, and a main reciprocative implement which is reciprocatively held by the housing. The rotor loosely retains an impact member. While the rotor is being rotated, the impact member repeatedly hits an impact receiving face of the main reciprocative implement, thereby causing the main reciprocative implement to reciprocate in a predetermined direction.
In the above rotary impacting apparatus, however, use is made of ball bearings for supporting the rotor within the housing. It has been found that the ball bearings, in repeated use, will often lose their initial function due to breakage of the ball retainers of the ball bearings for example. In such an unfavorable instance, the rotor may become unable to rotate smoothly or even unable to rotate at all.